Question

3. You make an empty lipid vesicle whose sole membrane protein is a version of the sodium-potassium pump found in neurons, that has been modified to pump one Na ion every time it pumps one K ion. It is oriented in the membrane the same way it is in neurons a) What would you expect to happen if you placed this vesicle in a solution containing only an equal concentration of Na* and K* ions, and filled the vesicle with the same solution? b) What would you expect to happen if you added ATP to the solutions in part a? c) What would you expect if the solutions instead contained only ATP and K ions? d) What would you expect if the solutions contained ATP and equal concentrations of Na" and K ions, but the membrane also contained K leak channels?

Answer 1

Answer

3 a) if that vesicle placed in the solution which contains the equal amount of K+ and Na+ ions, then there is no movement of the ions takes place because there is no gradient formation across the membranes.

Ionic gradient is the one which is the cause for the movement of the ions.

b) if the addition of ATP to the part of the solution then that triggers the movement of ions which is active transport through voltage gated ion channels.

c) If the solution contain only ATP and K+ ions then the distribution of that K+ ions occurs and when the ionic concentration becomes equal across the membrane then the movement stops.

d) If K+ leak channels or leakage channel are present then the ions readily leaks down their concentration gradient. this leakage channel is always open unlike the voltage gated channels have the gates which restricts the flow.